Patchwork [1/2] Fix off-by-1 error in RAM migration code

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Submitter Juan Quintela
Date Dec. 11, 2012, 12:34 p.m.
Message ID <1355229289-27574-2-git-send-email-quintela@redhat.com>
Download mbox | patch
Permalink /patch/205197/
State New
Headers show

Comments

Juan Quintela - Dec. 11, 2012, 12:34 p.m.
From: David Gibson <david@gibson.dropbear.id.au>

The code for migrating (or savevm-ing) memory pages starts off by creating
a dirty bitmap and filling it with 1s.  Except, actually, because bit
addresses are 0-based it fills every bit except bit 0 with 1s and puts an
extra 1 beyond the end of the bitmap, potentially corrupting unrelated
memory.  Oops.  This patch fixes it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 arch_init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/arch_init.c b/arch_init.c
index e6effe8..b75a4c5 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -568,7 +568,7 @@  static int ram_save_setup(QEMUFile *f, void *opaque)
     int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;

     migration_bitmap = bitmap_new(ram_pages);
-    bitmap_set(migration_bitmap, 1, ram_pages);
+    bitmap_set(migration_bitmap, 0, ram_pages);
     migration_dirty_pages = ram_pages;

     bytes_transferred = 0;